Charbel Saade

A reduced contrast volume acquisition regimen based on cardiovascular dynamics improves visualisation of head and neck vasculature with carotid MDCT angiography

PURPOSE To investigate enhancement of head and neck arteries during carotid computed tomography angiography using a reduced volume contrast regimen and craniocaudal scan acquisition. MATERIALS AND METHODS Two hundred and two patients underwent carotid angiography using a 64 channel computed tomography scanner. Patients were allocated to one of two acquisition/contrast regimens: regimen A, the departments standard protocol, consisting of a caudocranial scan direction with 100mL of contrast intravenously; regimen B, involving a craniocaudal scan direction and approximately 50 mL of contrast using a timing dictated by patient hemodynamics. Attenuation profiles of cranial arteries and veins in 6 anatomical segments were assessed and arteriovenous contrast ratios (AVCR) calculated. Receiver operating characteristic (ROC) analysis was performed using DBM methodology. RESULTS Arterial attenuation was up to 54% (p<0.01) higher following regimen B compared with A. Attenuation in the veins were significantly lower in regimen B than in regimen A with a maximum reduction of up to 93% (p<0.0001). With regimen B, there were significant (p<0.0001) improvements in AVCR at a variety of anatomical sites. The ROC analysis demonstrated a significantly higher Az score for the novel regimen compared with regimen A (p<0.002) with inter-neuroradiologist agreement increasing from poor to moderate. CONCLUSION Significant improvements in visualisation of head and neck arterial vasculature can be achieved with a CT acquisition regimen using low contrast volume and injection timing based on patient specific contrast formula and craniocaudal scan direction.

Caudocranial scan direction and patient-specific injection protocols optimize ecg-gated and non-gated thoracic CTA

Objectives Caudocranial scan direction and contrast injection timing based on measured patient vessel dynamics can significantly improve artery opacification and reduce contrast dose in the assessment of acute aortic syndrome using gated and non–gated thoracic CTA. This study aimed to investigate enhancement of the thoracic aorta using caudocranial scan direction and a patient-specific contrast regimen. Methods Electrocardiogram–gated (n = 120) and non–gated (n = 200) thoracic computed tomography angiography was performed on patients with nontraumatic acute aortic syndrome. Patients were assigned to one of 2 acquisition/contrast regimens, namely, regimen A, craniocaudal scan direction with 120 mL contrast, and regimen B, caudocranial scan direction using a patient-specific contrast formula. Opacity of 9 arterial and venous segments was measured, arteriovenous contrast ratio calculated, and values compared using Mann-Whitney U statistics. Receiver operating characteristic analyses and visual grading characteristic assessed diagnostic efficacy and clinical image quality. Interobserver variations were investigated using &kgr; methods. Results Regimen B when compared to A, for both scanning/contrast techniques, demonstrated higher opacification in the aorta (P < 0.01) and lower opacification in the venous system (P < 0.0001). For protocol B, arteriovenous contrast ratio was significantly increased (P < 0.0001) and mean contrast volume reduced (P < 0.05) during gated [94 (10 mL)] and non–gated [78 (5 mL)] thoracic computed tomography angiography compared to A. Receiver operating characteristic analysis Az scores and interobserver agreement were significantly higher with regimen B than A (P < 0.05). Conclusions Caudocranial scan direction and injection timing based on patient-specific vessel dynamics can optimize artery opacification and diagnostic efficacy while reducing contrast volumes.

Multidetector computed tomography in the evaluation of cirsoid aneurysm of the scalp--a manifestation of trauma.

Cirsoid aneurysms of the scalp are a rare abnormality with severe cosmetic deformity and possibly of severe hemorrhage. They present as a diagnostic and management challenge, but evaluation with multidetector computed tomography is useful in the diagnosis and treatment planning of these clinically complex disorders of the extracranial circulation. We present a case report of a 38-year-old New Caledonian male who had a large pulsatile mass in his scalp, which had progressively increased in size since the age of 17 years. The clinical and imaging features are outlined, in addition to treatment and prognosis.

MDCT Venography Evaluation of a Rare. Collateral Vein Draining from the Left Subclavian Vein to the Great Cardiac Vein

Congenital vascular anomalies of the venous drainage in the chest affect both cardiac and non-cardiac structures. Collateral venous drainage from the left subclavian vein to the great cardiac vein is a rare venous drainage pattern. These anomalies present a diagnostic challenge. Multi-detector computed tomography (MDCT) is useful in the diagnosis and treatment planning of these clinically complex disorders. We present a case report of an 18-year-old Caucasian male who came to our institute for evaluation of venous drainage patterns to the heart. We describe the contrast technique of bilateral dual injection MDCT venography and the imaging features of the venous drainage patterns to the heart.

Comparison of Standard and Quadruple-Phase Contrast Material Injection for Artifacts, Image Quality, and Radiation Dose in the Evaluation of Head and Neck Cancer Metastases.

PURPOSE To investigate opacification of head and neck vasculature during computed tomography (CT) of supraclavicular lymph nodes with a quadruple-phase contrast media and saline dual-injection protocol. MATERIALS AND METHODS This retrospective study was institutional review board approved. In 180 consecutive patients, routine head and neck CT was performed with one of two protocols: protocol A, craniocaudal scan direction with 100 mL of contrast material injected intravenously as a single bolus; or protocol B, 100 mL of contrast material injected in four phases (phases 1-2, 60 mL of contrast material and saline injected at 2.5 mL/sec; phases 3-4, 40 mL of contrast material and saline injected at 2.5 mL/sec); both protocols had a fixed scan delay of 70 seconds. Attenuation of supraclavicular arteries and veins was measured with arteriovenous contrast ratio (AVCR) and contrast-to-noise ratio (CNR). Effective dose was calculated. Data were compared with the two-sample t test. Receiver operating characteristic (ROC) and visual grading characteristic analyses were performed. RESULTS Arterial attenuation was up to 20% higher (P < .05) after protocol B (mean ± standard deviation, 234.5 HU ± 33.2) than protocol A (160.0 HU ± 29.5). Venous system attenuation was significantly lower in protocol B (164.0 HU ± 17.0) than in protocol A (664.0 HU ± 12.0), with up to a 75% reduction (P < .0001). Protocol B generated significant (P < .0001) improvements in AVCR at multiple anatomic sites. At all anatomic levels, mean CNR with protocol B (34.4 HU ± 9.0) was significantly higher than that with protocol A (14.5 HU ± 14.0) (P < .0313). Effective dose was significantly reduced with protocol B (2.6 mSv ± 0.4 vs 3.2 mSv ± 0.8 with protocol A; P < .0041). ROC analysis demonstrated significantly higher area under the ROC curve for protocol B (P < .0022), with interreader agreement increasing from poor to excellent in lymph node visualization. CONCLUSION Significant improvement in lymph node visualization at the cervicothoracic junction is achieved with a quadruple-phase contrast media injection protocol.

Exponentially Decelerated Contrast Media Injection Rate Combined With a Novel Patient-Specific Contrast Formula Reduces Contrast Volume Administration and Radiation Dose During Computed Tomography Pulmonary Angiography.

Clinical Relevance Matching contrast injection timing with vessel dynamics significantly improves vessel opacification and reduces contrast dose in the assessment of pulmonary embolism during computed tomography (CT) pulmonary angiography. Purpose The aim of this study was to investigate opacification of the pulmonary vasculature (PV) during CT pulmonary angiography using a patient-specific contrast formula (PSCF) and exponentially decelerated contrast media (EDCM) injection rate. Materials and Methods Institutional review board approved this retrospective study. Computed tomography pulmonary angiography was performed on 200 patients with suspected pulmonary embolism using a 64-channel CT scanner. Patient demographics were equally distributed. Patients were randomly assigned to 2 equal protocol groups: protocol A used a PSCF, and protocol B involved the use of a PSCF combined with EDCM. The mean cross-sectional opacification profile of 8 central and 11 peripheral PVs were measured for each patient, and arteriovenous contrast ratio was calculated. Protocols were compared using Mann-Whitney U nonparametric statistics. Jackknife alternative free-response receiver operating characteristic analyses were used to assess diagnostic efficacy. Interobserver variations were investigated using kappa methods. Results A number of pulmonary arteries demonstrated increases in opacification (P < 0.02) for protocol B compared with A, whereas opacification in all veins was reduced in protocol B (P < 0.03). Subsequently, increased arteriovenous contrast ratio in protocol B compared with A was observed at all anatomic locations (P < 0.0002). An increase in jackknife alternative free-response receiver operating characteristic figure of merit (P < 0.0002) and interobserver variation was observed with protocol B compared with protocol A (&kgr; = 0.3-0.73). Mean contrast volume was reduced in protocol B (29 [4] mL) compared with protocol A (33 [9] mL). Mean effective radiation dose in protocol B (1.2 [0.4] mSv) was reduced by 14% compared with protocol A (1.4 [0.6] mSv). Conclusions Significant improvements in visualization of the PV can be achieved with a low contrast volume using an EDCM and PSCF. The reduced risk of cancer induction is highlighted.

Contrast medium administration and image acquisition parameters in renal CT angiography: what radiologists need to know

Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged. Poor synchronization between scanner and contrast media administration have reduced the consistency in image quality with poor spatial and contrast resolution. Comprehensive understanding of contrast media dynamics is essential in the design and implementation of contrast administration and image acquisition protocols. This review includes an overview of the parameters affecting renal artery opacification and current protocol strategies to achieve optimal image quality during renal CT angiography with iodinated contrast media, with current safety issues highlighted.

MDCT angiography of the major congenital anomalies of the extracranial arteries: Pictorial review

Multidetector computed tomographic angiography is becoming the modality of choice for evaluation of the supra‐aortic circulation in acute stroke imaging. Variations of the supra‐aortic circulation, in particular of the extracranial arteries, are common. This article aims to provide a pictorial description of the variant anatomy of the aortic arch and extracranial arteries. Knowledge of the presence and clinical relevance of normal variants such as anomalies, duplications and embryological persistence plays a clinically relevant role in the diagnosis and management of neurological and surgical conditions, particularly as we enter an era of increasing extracranial intervention.

256 Slice Multi-detector Computed Tomography Thoracic Aorta Computed Tomography Angiography: Improved Luminal Opacification Using a Patient-Specific Contrast Protocol and Caudocranial Scan Acquisition.

Clinical Relevance Statement Caudocranial scan direction and contrast injection timing based on measured patient vessel dynamics can significantly improve arterial and aneurysmal opacification and reduce both contrast and radiation dose in the assessment of thoracic aortic aneurysms (TAA) using helical thoracic computed tomography angiography (CTA). Objectives To investigate opacification of the thoracic aorta and TAA using a caudocranial scan direction and a patient-specific contrast protocol. Materials and Methods Thoracic aortic CTA was performed in 160 consecutive patients with suspected TAA using a 256-slice computed tomography scanner and a dual barrel contrast injector. Patients were subjected in equal numbers to one of two contrast protocols. Patient age and sex were equally distributed across both groups. Protocol A, the departments standard protocol, consisted of a craniocaudal scan direction with 100 mL of contrast, intravenously injected at a flow rate of 4.5 mL/s. Protocol B involved a caudocranial scan direction and a novel contrast formula based on patient cardiovascular dynamics, followed by 100 mL of saline at 4.5 mL/s. Each scan acquisition comprised of 120 kVp, 200 mA with modulation, temporal resolution 0.27 seconds, and pitch 0.889:1. The dose length product was measured between each protocol and data generated were compared using Mann-Whitney U nonparametric statistics. Receiver operating characteristic analysis, visual grading characteristic (VGC), and &kgr; analyses were performed. Results Mean opacification in the thoracic aorta and aneurysm measured was 24 % and 55%, respectively. The mean contrast volume was significantly lower in protocol B (73 ± 10 mL) compared with A (100 ± 1 mL) (P<0.001). The contrast-to-noise ratio demonstrated significant differences between the protocols (protocol A, 18.2 ± 12.9; protocol B, 29.7 ± 0.61; P < 0.003). Mean effective dose in protocol B (2.6 ± 0.4 mSv) was reduced by 19% compared with A (3.2 ± 0.8 mSv) (P < 0.004). Aneurysmal detectability demonstrated significant increases by receiver operating characteristic and visual grading characteristic analysis for protocol B compared with A (P < 0.02), and reader agreement increased from poor to excellent. Conclusions Significant increase in the visualization of TAAs following a caudocranial scan direction during helical thoracic CTA can be achieved using low-contrast volume based on patient-specific contrast formula.

Imaging in multiple sclerosis: A new spin on lesions

This article evaluates the most relevant state‐of‐the‐art magnetic resonance (MR) techniques that are clinically available to investigate multiple sclerosis (MS). The presence of hypo‐ and hyperintense lesions on T1‐ and T2‐weighted magnetic resonance imaging (MRI) sequences in white matter (WM) is a common finding that is occasionally a diagnostic challenge for the radiologist. The technical requirements and how they may help to understand, classify or follow‐up these pathologies are briefly summarized. The gold standard for MS diagnosis is pathological correlation. Yet due to limited availability of biopsy and autopsy material, there is a high demand for imaging as a diagnostic as well as prognostic indicator. With the progress in MRI during the last decade, MRI now plays a leading role in the diagnosis and follow‐up of MS. A number of correlative pathological and MR studies have helped to define pathological substrates of MS in focal lesions and normal appearing white matter (NAWM). Vascular spaces mimicking MS lesions have been minimized by the enhanced differentiation of WM and grey (GM) matter parenchyma. The aim of this article is to enhance the current understanding of histopathology and radiological characteristics of MS lesions in space and time.